This invention relates generally to flexible packages, and more particularly to flexible packages for holding products, such as foods, under vacuum therein, and which once opened are arranged to be repeatedly re-opened and re-closed, while keeping the contents fresh.
Various types of flexible packages for holding particulate materials, e.g., ground or whole bean coffee, chemicals, etc., under vacuum therein have been disclosed in the patent literature and are commercially available today. Examples of such packages are found in the following U.S. Pat. Nos.: 4,576,285 (Goglio), 4,705,174 (Goglio), and 4,913,561 (Beer).
The major advantages of flexible packaging, as compared to relatively rigid packaging, e.g., cartons, are that until the flexible package is filled it takes up very little volume, and after it is emptied of its contents it readily collapses, thereby reducing its volume to approximately that of the unfilled package. The former characteristic is a significant advantage insofar as storage is concerned, while the latter characteristic is a significant advantage from the standpoint of being disposable.
One common type of flexible package for holding goods under vacuum until the package is opened is the so-called "gusseted" package or bag. Typically such a package is formed from a web of flexible stock material, e.g., polyethylene, polyester, polypropylene, metal foil, and combinations thereof in single or multiple plies, into a tubular body, having a face panel, a back panel, and a pair of gusseted sides. Each gusseted side is formed by a pair of gusset sections and a central fold edge interposed between a pair of outer fold edges. The lower end of the bag is commonly permanently sealed, e.g., heat sealed, along a line extending transversely across the width of the bag close to its bottom edge. The top of the bag is commonly sealed transversely across the entire width of the bag in a number of ways to maintain the contents under vacuum until the bag is opened. Such action is frequently accomplished via a readily openable mouth, which when opened provides access to the contents of the bag. For example, in one prior art package the top seal is made peelable by modifying the sealant layer with a peelable coating or incompatible additive. Thus, when the seal is peeled apart the unsealed portions form an open mouth through which the contents of the package may be removed. Another approach to providing an opening or mouth for a flexible package is that of the heretofore identified U.S. Pat. No. 4,705,174 (Goglio). That package includes a peel strip applied to the inner surface of the package below the top edges. The strip provides an air-tight interfacial seal which can be readily peeled apart to provide access to the interior of the package. Another approach to providing an opening or mouth for a flexible package is to score the upper flap of the package by laser or mechanical means through a tear initiation resistant layer(s) of the package structure. In this way the package can be opened by tearing away the scored area to form the package's mouth.
Gusseted bags, particularly those for foods, frequently make use of a plastic coated wire tie to serve as closure for the bag. In particular, the wire tie is designed to close the mouth of the bag after it has been initially opened so that the re-closed bag will keep its contents fresh. Whether or not such wire-tie closures effectively provide a positive means of re-closing a gusseted package is open to debate. Moreover, the effectiveness of such closures is frequently dependent upon the manner in which the wire tie is used. Thus, there is a perception in some quarters of the consuming public that a wire-tie package cannot be re-closed securely enough to maintain product freshness over an extended period of time. Therefore, such packages have not been fully accepted as being truly reclosable.
Non-gusseted flexible packages, such as stand-up pouches, are commercially available and typically include so-called "zipper-type" closures. Examples, of such packages are shown in U.S. Pat. Nos. 5,059,036 (Richison et al.), and 5,147,272 (Richison et al.). These zipper-type closures are generally perceived by the consuming public as providing for a more effective reclosure of the flexible pouch after it has been initially opened than twist or wire tie closures. In fact, zipper-type closures may be more effective than wire-tie closures. At the very least they are easier to use, and not prone to loss or misplacement. Thus, stand-up, flexible pouches with zipper-type closures have gained wide acceptance by the consumer.
While the stand-up, zipper-closure type pouch offers advantages over a gusseted flexible package insofar as actual or perceived reclosability is concerned, its shape does not allow efficient use of case packing and retail shelf space, as does a gusseted package. In addition, the stand-up pouch cannot be stacked readily, if at all.
In U.S. Pat. No. 5,692,837 (Beer), which is assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein there is disclosed a gusseted flexible package having a integrated snap closure for re-closing and resealing the package after it has been initially opened. In particular, that package has an interior for initially holding some product, e.g., whole coffee bean or ground coffee, under vacuum, and which includes a mouth portion arranged to be peeled open to provide access to the contents of the package. The package is formed of a flexible material and includes a front panel, a rear panel, and a pair of opposed side gussets. The panels and gussets each include atop portion, which between them define the package's mouth. A peelable closure is provided within the mouth. A snap closure is provided above the peelable closure. The package is arranged to be sealed under vacuum, with the peelable closure maintaining the vacuum within the package until it is peeled open. The snap closure comprises a pair of snap strip members secured to respective portions of the front and rear panel. The snap strip portions are arranged to be releasably snap fit together with portions of the closure extending through opening in the side gussets, so that the snap strip portions can be opened and re-closed after the peelable closure has been peeled open in order to provide repeated access to the interior of the package, while minimizing the ingress of air into the package when it is closed.
Other references involving closures for packages are found in U.S. Pat. Nos.: 4,988,216 (Lyman), and 5,037,138 (McClintock et al.), and in Japanese Application 6127557 (5/1994), and United Kingdom Patent 1,008,068 (10/1965)
While the inventions of the aforementioned prior art are suitable for their intended purposes, a need still exists for snap closures for use on gusseted packages and for gusseted packages which include snap closures not requiring holes or openings in the gussets of the package to effect reclosure of the package.